I have:
2 zebra nerites, 2 red onion, 1 black helmet and 1 waigiensis in my 180 litre and 1 red onion in the shrimp tank (though I may move it into the 180 litre as the shrimps seem to eat all the algae in there)
GH 7 dH
KH 3.3 dH
pH 7.2
One of the red onions in the 180 litre was bought in July 2011. I keep records of everything I buy including snails.
The other two and the zebras are more recent additions, August 2020. They were from eBay, so called mixed species of several varieties but they sent 3 zebra and 2 red onion. One of the zebras laid eggs everywhere. It only stopped when one of them died, presumably the egg layer.
The black helmet and waigiensis were bought October last year.
I bought a zebra nerite in July 2011 at the same time as the red onion. It died in July 2020, 9 years after I bought it.